1. Field of the Invention
The present invention relates to an electrostatic ink jet recording apparatus, in particular, to an electrostatic ink jet recording apparatus that is used for a printer, a facsimile machine, a copy machine, and so forth and that uses an ink of which toner particles are dispersed in a carrier solution and jetted by an electrostatic force.
2. Description of the Related Art
A variety of ink jet recording systems have been proposed because of their advantages such as direct recording on plain paper and low noise. As one of such systems, an ink recording head has been disclosed as Japanese Patent Laid-Open Publication No. 56-167473. With reference to FIG. 6, the structure of the related art reference will be described.
In an ink jet recorder, a large number of electrodes 52 are placed at an inner side of an ink jet port 51 of a recording head. Ink in the jet port 51 is selectively jetted through the port by selectively applying a high voltage pulse between the electrodes 52 and a grounded conductor 59 at the side of record paper 60 corresponding to a picture signal. In the ink jet recorder, the jet port 51 is divided into an upper part 51a and a lower part 51b with a partition 55 in the slit-form jet port 51, which is formed with an upper plate 56 and a lower plate 57. A large number of electrodes 52 are disposed at the inside of divided jet ports 51a and 51b (upper plate and lower plate surfaces and/or the surfaces of the divided plates). By applying a high voltage to some electrodes and a low voltage to an electrode positioned on the right or left of the electrode, and ink jet dot moves to the high voltage side.
Ink placed in an ink chamber 54 reaches the ink ejection port 51. The ink at the ink jet port 51a and 51b forms a linear meniscus. When a high voltage of around 2 kV is applied from a terminal 58 to a selected electrode 52, the ink is jetted from the position of the electrode at which such a high voltage is applied. The ink is accelerated by an electric field with a conductive roller 59 and then adhered to record paper 60. Thus, by selecting a plurality of electrodes and applying a high voltage thereto at the same time, a pattern of one line can be recorded. With the record paper 60 moved, characters, figures, and so forth can be recorded as dots of the ink.
Another related art reference that has been disclosed as PCT Laid-Open Publication NO. WO 93/11866 is an electrostatic ink jet recording apparatus. The apparatus comprises an electrostatic ink jet recording head and a counter electrode. The counter electrode causes an electric field to be formed with a counter electrode against the ink jet recording head disposed on the rear surface of the record paper. The ink jet recording head has an ink chamber and an ejection electrode. The ink chamber temporarily stores an ink solution supplied from an ink tank or the like. The ejection electrode is disposed at an edge portion of the ink chamber. The ink jet recording head is disposed opposite to the counter electrode. The ink solution in the ink chamber is supplied to the edge of the ejection electrode due to the surface tension. Thus, an ink meniscus is formed at the edge of the ejection electrode. The ink solution used for the ink jet recording head contains a coloring charge particles. The charge particles are positively charged with a zeta voltage.
When a positive voltage is applied to the ejection electrode, the voltage of the ink solution increases. When Coulomb force that works between the charge particles at the edge of the ejection electrode and the counter electrode largely exceeds the surface tension of the ink solution, agglomeration of the charge particles with a small amount of ink solution is jetted from the edge position of the ejection electrode to the counter electrode. The charge particles adhere to the front surface of the record medium. In such a method, with the voltage to the ejection electrode, agglomeration of the charge particles is successively jetted from the edge of the election electrode to the front surface of the record medium and thereby data is recorded.